Preheat oven to 375F. Butter well 9 - 3" muffin-pan cups.
With mixer at low speed (or with hand beater) beat eggs slightly; beat in
milk and melted butter; then gradually beat in flour and salt. Place a
spoonful of parmesan in each muffin cup, dividing evenly among all. Pour
batter in cups, dividing evenly among all.
Bake popovers 40 minutes; then remove from oven. Quickly cut slit in side of
each to let out steam; return to oven for 10 minutes or until tops are very
firm, crisp, and brown. Immediately remove from pan and serve.